High dielectric constant type ceramic composition

ABSTRACT

A basic ceramic composition of high dielectric constant type ceramic composition comprises from 68.67 to 69.19% of PbO, from 3.67 to 4.09% of MgO, from 24.17 to 26.99% of Nb 2  O 5  and from 0.25 to 2.97% of TiO 2 , all percentages being by weight. Modified composition may comprise additive of Pb(Mn 2/3  W 1/3 )O 3 , Pb(Mn 1/3  Nb 2/3 )O 3 , Pb(Mn 1/3  Ta 2/3 )O 3 , Pb(Mn 1/2  W 1/2 )O 3 , MnO, and MgO. Modified composition may comprise Ba, Sr and Ca, which replace Pb of the basic ceramic composition. In a modified composition, the content of B site elements may be larger than that of A site element of an ABO 3  crystal of the high dielectric constant type ceramic composition. A high dielectric constant, low dielectric loss, low temperature dependence of capacitance, high insulation resistance and a low sintering temperature are provided by the ceramic compositions of the present invention.

The present invention relates to a ceramic dielectric composition, which can be classified into a high dielectric constant type and a temperature-compensating type, and relates, more particularly, to the former type ceramic dielectric composition, which is characterized by being sintered at a relatively low temperature, exhibiting a high dielectric constant, a reduced dielectric loss, and a low dependence of the properties upon temperature. This ceramic dielectric composition is suitable for "high dielectric constant" capacitors of a compact-type with large capacity, such as laminar capacitors.

Most ceramic dielectrics heretofore proposed for high dielectric constant capacitors contain, as the basic ingredient, a compound having a perovskite structure, such as barium titanate (BaTiO₃), barium stannate (BaSnO₃) and calcium titanate (CaTiO₃). Depending upon various requirements in using the dielectrics in the capacitors, an additional element, which constitutes the substitutional solid solution of the basic ingredient, is used for increasing the dielectric constant of ceramic dielectrics. A compound having a structure different from the perovskite structure, can be mixed with the basic ingredient so as to increase the dielectric constant of the ceramic dielectrics. In the most widely used dielectrics, the dielectric constant thereof is increased as mentioned above. In such increase of the dielectric constant, the Curie point of the dielectrics can be adjusted to a value corresponding to that at room temperature, so as to increase the dielectric constant to the maximum value, for example from 4000 to 20,000, which can be achieved by a dielectric comprising a particular basic ingredient. The temperature dependence of the dielectric constant of such dielectric is, however, increased by the increase of the dielectric constant. On the other hand, when the temperature dependence of dielectric constant is decreased, the maximum value of dielectric constant is disadvantageously decreased.

Suitable sintering temperatures of the ceramic dielectric compositions mentioned above are generally 1200° to 1400° C. Accordingly, a large amount of heat energy is required for sintering. In addition, due to the high sintering temperature of from 1200° to 1400° C., the sintering furnace is considerably deteriorated and eroded during the sintering. As a result, the maintainance cost of the sintering furnace becomes, therefore, expensive.

Recently, a ceramic capacitor which is more compact and of more improved capacity, and possesses a high reliability, has been desired in the field, including the communication industry. Thus, a capacitor of a thin ceramic film having a 0.1 to 0.2 mm thickness and a ceramic laminar capacitor composed of a plurality of superimposed laminae, each having a thickness of approximately 50 microns or less, have been put to practical use. In the production of the laminar ceramic capacitor, the laminated dielectric body must be sintered, while the internal electrodes of the ceramic capacitor are inserted in the laminated body. Since the sintering temperature of the coventional ceramic dielectrics is high, a noble metal, such as platinum or palladium, or their alloys, had to be used as the internal electrodes.

It is proposed in German Offenlegungsschrift No. 27 01 411 that the sintering temperature of a high dielectric constant type ceramic composition be lowered to 1000° C. or less by preparing the composition from two components, i.e. Pb(Fe_(2/3) W_(1/3))_(x) O₃ and Pb(Fe_(1/2) Nb_(1/2))_(1-x) O₃. Since the laminated ceramic capacitor can be produced by a low sintering temperature of less than 1000° C., according to the proposal in the German Offenlegungsschrift cheap materials such as silver, nickel, aluminum, and the like, can be used as the internal electrodes of the cpacitor, and therefore, the production cost of the capacitor can advantageously be lowered from that of the prior art.

It is an object of the present invention to provide ceramic dielectric compositions which: can be sintered at a relatively low sintering temperature; have a high insulation resistance; have a relatively high dielectric constant in the high dielectric type ceramic dielectrics, have a low dielectric loss, and; have a low dependence of dielectric constant upon temperature.

It is another object of the present invention to provide ceramic dielectric compositions particularly suitable for a high dielectric constant type capacitor of a compact and laminar type.

In accordance with the objects of the present invention there is provided a high dielectric constant type, ceramic composition, hereinafter referred to as the basic ceramic composition, which comprises from 68.67 to 69.19% of PbO, from 3.67 to 4.09% of MgO, 24.17 to 26.99% of Nb₂ O₅ and from 0.25 to 2.97% of TiO₂, all percentages being by weight based on the basic ceramic composition. The basic ceramic composition is mainly composed of a double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃ and a double oxide of PbTiO₃. The proportions of Pb(Mg_(1/3) Nb_(2/3))O₃ and TbTiO₃ are from 88.0 to 99.0 molar% and from 1.0 to 12.0 molar%, respectively. The crystal structure of these double oxides can be generally expressed in an A_(x) B_(y) O₃ form, wherein each of the A and B components occupy predetermined positions of a crystal lattice, i.e. the perovskite lattice. The A component is lead (Pb), and the B component is magnesium (Mg), niobium (Nb) or titanium (Ti). The values of x and y are 1.00 in the basic ceramic composition.

Provided in accordance with the objects of the present invention are the following modified ceramic compositions.

A. A modified ceramic composition which comprises the basic ceramic composition and Pb(Mn_(2/3) W_(1/3))O₃ in an amount of from 0.05 to 5.0 parts by weight, based on 100 weight parts of the basic ceramic composition.

B. A modified ceramic composition which comprises the basic ceramic composition and Pb(Mn_(1/3) Nb_(2/3))O₃ in an amount of from 0.05 to 5.0 parts by weight, based on 100 weight parts of the basic ceramic composition.

C. A modified ceramic composition which comprises the basic ceramic composition and Pb(Mn_(1/3) Ta_(2/3))O₃ in an amount of from 0.05 to 5.0 parts by weight based on 100 weight parts of the basic ceramic composition.

D. A modified ceramic composition which comprises the basic ceramic composition and Pb(Mn_(1/2) W_(1/2))O₃ in an amount of from 0.05 to 5.0 parts by weight, based on 100 weight parts of the basic ceramic composition.

E. A modified ceramic composition which comprises the basic ceramic composition and MnO in an amount of from 0.001 to 1.5 parts by weight, based on 100 weight parts of the basic ceramic composition.

F. A modified composition which comprises an MgO oxide additive in addition to the double oxides mentioned above, i.e. Pb(Mg_(1/3) Nb_(2/3))O₃ and PbTiO₃, and in which the amount of the MgO oxide additive is not more than 25 parts by weight, based on 100 parts by weight of an MgO oxide contained in the double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃.

The additive of Pb(Mn_(1/3) Nb_(2/3))O₃ in an amount of from 0.05 to 5.0 parts by weight may be added to 100 parts by weight of the double oxides.

G. A modified composition which comprises at least one additive element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca) in an amount of not more tha 10 atomic parts, based on 100 atomic parts of lead (Pb) contained in the double oxides, mentioned above, i.e. Pb(Mg_(1/3) Nb_(2/3))O₃ and PbTiO₃.

H. A modified composition which comprises the A and B components mentioned above at a molar ratio of A/B of from 0.9200 to less than 1.0000.

I. A modified composition which comprises from 60 to 98 molar% of Pb(Mg_(1/3) Nb_(2/3))O₃ and from 2 to 40 molar% of PbTiO₃, and further, from 0.2 to 8.0 parts by weight of at least one additive oxide selected from the group consisting of Bi₂ O₃ and WO₃, based on 100 parts by weight of total weight of Pb(Mg_(1/3) Nb_(2/3))O₃ and PbTiO₃.

The properties and the embodiments of the ceramic compositions according to the present invention will now be illustrated.

Every high dielectric constant type ceramic composition according to the present invention can be sintered at a relatively low temperature of 1130° C. or lower. In the basic ceramic composition, the contents of lead oxide (PbO), magnesium oxide (MgO), titanium oxide (TiO₂) and niobium oxide (Nb₂ O₅) are determined based on the following. When the content lead oxide (PbO) is less than 68.67% and the content of magnesium oxide (MgO) is more than 4.09%, the dielectric constant is too low to use the ceramic dielectrics on a practical basis, and the sintering temperature is disadvantageously high. When the content of titanium oxide (TiO₂) is less than 0.25% and the content of niobium oxide (Nb₂ O₅) is more than 26.99%, the dielectric constant is too low and the sintering temperature is high as mentioned above. When the content of lead oxide (PbO) is more than 69.19%, the content of magnesium oxide (MgO) is less than 3.67%, the content of niobium oxide (Nb₂ O₅) is less than 24.17 % and the content of titanium oxide (TiO₂) is more than 2.97%, the dielectric constant is too low and the dielectric loss is too high to use the ceramic dielectrics on a practical basis.

In the basic ceramic composition which is capable of being sintered at a relatively low temperature according to the present invention, the relative dielectric constant (ε_(s)), which is simply referred to as the dielectric constant in the present specification, may be from 14000 to 20000. In the basic ceramic composition, the insulation resistance is more than 1×10¹⁰ (ω). Furthermore, the dielectric loss (tan δ at 1 KHz) is from 0.2 to 4.8% and is, therefore, low. A preferable basic ceramic composition comprises from 68.67 to 68.95% of PbO, from 3.86 to 4.09% of MgO, from 25.46 to 26.99% of Nb₂ O₅ and from 0.25 to 1.73% of TiO₂. The insulation resistance (IR) described in the present specification indicates the resistance of a ceramic composition having a thickness of approximately 0.5 mm. A direct current of 500 V is applied to this composition at 20° C. when measuring the insulation resistance. The temperature dependence of the dielectric constant (ε_(s)) described in the present specification indicates: ##EQU1## The term "temperature variance" of the dielectric constant used in the present specification indicates the absolute value of Δε_(s).

By adding a particular amount of the additives Pb(Mn_(2/3) W_(1/3))O₃, Pb(Mn_(1/3) Nb_(2/3))O₃, Pb(Mn_(1/3) Ta_(2/3))O₃, Pb(Mn_(1/2) W_(1/2))O₃, and MnO into the basic ceramic composition, several or all of the electrical properties of the modified ceramic compositions can be improved to levels more preferable than those of the basic ceramic composition.

The modified ceramic composition mentioned in item A, above, containing Pb(Mn_(2/3) W_(1/3))O₃, and capable of being sintered at a relatively low temperature, may exhibit dielectric constant (ε_(s)) of from approximately 14,000 to 22,000. The dielectric loss (tan δ at 1 KHz) is very low because of the Pb(Mn_(2/3) W_(1/3))O₃ additive ranges from approximately 0.1 to 1.2%. The modified composition mentioned in item A, above, may have a low temperature variance of less tha 65% and an insulation resistance (IR) of from 7×10¹⁰ to 3×10¹² ω. At a Pb(Mn_(2/3) W_(1/3))O₃ content of less than 0.05 parts by weight, the insulation resistance (IR) and the dielectric loss (tan δ) are not improved appreciably when compared with those of the basic ceramic composition. At a Pb(Mn_(2/3) W_(1/3))O₃ content of more than 5.00 parts by weight, the dielectric constant is too low to use the modified ceramic composition on a practical basis. The additive content is preferably from 0.1 to 0.6 parts by weight.

The modified ceramic composition mentioned in item B, above, containing an additive of Pb(Mn_(1/3) Nb_(2/3))O₃ capable of being sintered at a relatively low temperature, may exhibit a dielectric constant (ε_(s)) of from approximately 13700 to 22900, a dielectric loss (tan δ at 1 KHz) of from 0.1 to 1.4%, and an insulation resistance (IR) of from 7×10¹⁰ to 1×10¹² Ω. The additive of Pb(Mn_(1/3) Nb_(2/3))O₃ improves the dielectric loss (tan δ) and insulation resistance (IR) of the basic ceramic composition. At an additive content of less than 0.05 parts by weight, the insulation resistance (IR) and the dielectric loss (tan δ) are not improved enough. At an additive content of more than 5.0 parts by weight, the dielectric constant (ε_(s)) is too low to use the modified composition on a practical basis. The additive content is preferably from 0.1 to 1.0 part by weight.

The modified composition mentioned in item C, above, containing an additive of Pb(Mn_(1/3) Ta_(2/3))O₃ and capable of being sintered at a relatively low temperature, may exhibit a dielectric constant (ε_(s)) of from approximately 14,100 to 22,800, a dielectric loss (tan δ at 1 KHz) of from 0.1 to 1.5%, and an insulation resistance (R) of approximately to 2×10¹² Ω. The additive of Pb(Mn_(1/3) Ta_(2/3))O₃ improves the dielectric loss (tan δ) and insulation resistance (IR) of the basic ceramic composition. At an additive content of less than 0.05 parts by weight the dielectric loss (tan δ) and insulation resistance (IR) are not improved appreciably when compared with those of the basic ceramic composition. At an additive content of more than 5.0 parts by weight, the dielectric constant (ε_(s)) is too low to use the modified composition on a practical basis. The additive content is preferably from 0.5 to 3.0 parts by weight.

The modified composition mentioned in item D, above, containing an additive of Pb(Mn_(1/2) W_(1/2))O₃ and capable of being sintered at a relatively low temperature, may exhibit a dielectric constant (ε_(s)) of from approximately 13700 to 22900, a dielectric loss (tan δ at 1 KHz) of from 0.1 to 1.5% and an insulation resistance (IR) of from approximately 6×10¹⁰ to 2×10¹² Ω. The additive of Pb(Mn_(1/2) W_(1/2))O₃ improves the dielectric loss (tan δ) and insulation resistance (IR) of the basic ceramic composition. At an additive content of less than 0.05 parts by weight the dielectric loss (tan δ) and insulation resistance (IR) are not improved appreciably when compared with those of the basic ceramic composition. At an additive content of more than 5.0 parts by weight, the dielectric constant (ε_(s)) is to low to use the modified composition on a practical basis. The additive content is preferably from 0.1 to 1.5 parts by weight.

The modified composition mentioned in item E, above, containing an additive of MnO and capable of being sintered at a relatively low temperature, may exhibit a dielectric constant (ε_(s)) of from approximately 7000 to 21000, a dielectric loss (tan δ at 1 KHz) of from 0.1 to 1.5% and an insulation resistance (IR) of from 8×10¹⁰ to 1×10¹² Ω. The additive of MnO improves the dielectric loss (tan δ) and insulation resistance (IR) of the basic ceramic composition. At an additive content of less than 0.001 parts by weight of the dielectric loss (tan δ) and insulation resistance (IR) are not improved enough. At an additive content of more than 5.0 parts by weight, the dielectric constant (ε_(s)) is too low the use the modified composition on a practical basis. The additive content is preferably from 0.005 to 0.2 parts by weight.

The modified composition mentioned in item F, above, includes an Mg oxide additive in an amount of not more tha 25 weight parts, based on stoichiometrically calculated 100 parts by weight of MgO in the double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃. This modified composition can be sintered at a relatively low temperature and may exhibit a dielectric constant (ε_(s)) of from 19,800 to 30,100, which is remarkably increased over that of the basic ceramic composition due to the Mg oxide additive. In addition to the advantageously high dielectric constant (ε_(s)), the dielectric loss (tan δ at 1 KHz) is also low and may be approximately from 0.3 to 2.8%. When the content of the Mg oxide additive is more than 25 parts by weight, the dielectric constant (ε_(s)) cannot be improved appreciably when compared with those of the basic ceramic composition. The content of the Mg oxide additive is preferably from 3 to 9 parts by weight.

The modified composition mentioned in item G, above, contains an additive element(s) which replaces lead (Pb) occupying the A sites of the A_(x) B_(y) O₃ crystal. The modified composition can be sintered at a relatively low temperture of 1050° C. or less, and may exhibit a dielectric constant (ε_(s)) of 19400 to 22500, a dielectric loss (tan ε at 1 KHz) of from 0.2 to 2.8% and an insulation resistance (IR) of from 3×10¹⁰ to 5×10¹¹Ω. The additive element improves the dielectric constant (ε_(s)) and dielectric loss (tan δ). If the replacing amount of the additive element is more than 10 atomic parts, the dielectric constant cannot be improved appreciably when compared with those of the basic ceramic composition. The content of additive element is preferably from 3 to 10 atomic parts.

The modified composition mentioned in item H, above, comprises the A and B components not in identical molar amounts but the B component in a molar amount larger than that of the A component. In other words, the content of the elements of the B sites exceeds that of the A sites. Due to the excessive addition of the B sites element the dielectric constant (ε_(s)) is remarkably increased while the dielectric loss (tan δ) is maintained at a satisfactorily low level. The modified composition mentioned above can be sintered at 1100° C. or lower, and may exhibit a dielectric constant (ε_(s)) of from approximately 20,300 to 29,800, a dielectric loss (tan δ at 1 KHz) of from approximately 0.8 to 1.7% and an insulation resistance (IR) of from 7×10¹⁰ to 6×10¹¹ Ω. When the molar ratio of A/B is less than 0.9200 the dielectric constant is not improved significantly. A preferable molar ratio of A/B is from 0.950 to 0.982.

The modified composition mentioned in item I, above, can include the double oxides in a range broader than in the basic ceramic composition, due to the additive oxide of Bi₂ O₃ and or WO₃. The composition of from 60 to 98 molar% of Pb(Mg_(1/3) Nb_(2/3))O₃ and from 2 to 40 molar% of PbTiO₃ corresponds to a composition comprising from 68.72 to 70.55% of PbO, from 2.55 to 4.05% of MgO, from 16.80 to 26.73 of Nb₂ O₅ and from 0.49 to 10.10% of TiO₂, all percentages being by weight. The additive oxide improves the dielectric constant (ε_(s)), the dielectric loss (tan ε) and temperature variance of the Pb(Mg_(1/3) Nb_(2/3))O₃ and PbTiO₃ based composition. The modified composition can be sintered at a temperature of from 850° to 1100° C., and may exhibit dielectric constant (ε_(s)) of from 4,000 to 16,500, a dielectric loss (tan δ at 1 KHz) of from 1.3 to 2.8% and an insulation resistance (IR) of from 3×10¹⁰ to 8×10¹⁰ Ω.

At an additive oxide content of less than 0.2 parts by weight, the dielectric loss (tan δ) is too low to use the modified composition on a practical basis. At an additive oxide content of more than 8.0 parts by weight, the dielectric loss (tan δ) is considerably deteriorated and the temperature dependence of the capacitance is unstable, so that the modified composition cannot be used on a practical basis. The preferable contents of Pb(Mg_(1/3) Nb_(2/3))O₃ and PbTiO₃ are from 91 to 97 molar% and from 3 to 9 molar%, respectively. The preferable content of additive oxide is from 2 to 6 parts by weight.

The contents of the basic composition, or the additive composition, should be selected in accordance with the electrical properties to be specifically achieved. For example, when a high dielectric constant should be achieved, the preferable contents of the basic component: from 68.7 to 69.0% of PbO; from 3.85 to 4.05% of MgO; from 25.45 to 26.50% of Nb₂ O₅, and; from 0.70 to 1.75% of TiO₂. In addition, the preferable contents of the additive, element and oxide are: from 0.05 to 0.6 parts by weight of the additive oxides, and; from 1 to 10 atomic parts of at least one of Ba, Sr and Ca. Particularly advantageous are the modified composition mentioned in item H, above, and the modified composition mentioned in item F, above, having the MgO additive content of from 3 to 10 parts by weight.

When a low temperature variance should be achieved, the preferable contents of the additives are: from 0.05 to 2.0 parts by weight of Pb(Mn_(2/3) W_(1/3))O₃, Pb(Mn_(1/3) Nb_(2/3))O₃, Pb(Mn_(1/3) Ta_(2/3))O₃ and Pb(Mn_(1/2) W_(1/2))O₃, and; from 0.001 to 0.3 parts by weight of Mno.

A high insulation resistance (IR) and low dielectric loss (tan δ) can be obtained at an additive content of from 0.5 to 3.0 parts by weight of Pb(Mn_(2/3) W_(1/3))O₃, Pb(Mn_(1/3) Nb_(2/3))O₃, Pb(Mn_(1/3) Ta_(2/3))O₃ and Pb(Mn_(1/2) W_(1/2) O₃).

One of the properties which must be provided in any PbO containing ceramic is the property of preventing vaporization of the PbO during sintering. The manganese containing additives can effectively prevent the PbO vaporization and can thus contribute to the stabilization of the sintering process.

The ceramic dielectric compositions of the present invention may be prepared as follows. Finely divided particles or powders of respective metal oxides are blended with each other using a ball mill and shaped into a suitable form. After a binder is added to the powders, the powders are press-formed for example, into discs. The discs are sintered at a temperature of from 850° to 900° C. for a period of one to two hours, enclosed in a magnesia ceramic vessel. Each disc is plated with a silver, nickel or aluminum electrode. Instead of metal oxides, metal carbonates may be used.

The present invention will now be explained further in detail by way of examples.

EXAMPLE 1

The weights of lead oxide (PbO), magnesium oxide (MgO), niobium oxide (Nb₂ O₅) and titanium oxide (TiO₂), all in the powdered form, were adjusted so that the oxides were contained in the ceramic composition in the proportions as shown in Table 1, below. These oxide mixtures, serving as the raw material of the ceramic composition, were blended under a moist condition in a bowl made of an organic resin, and thereafter, presintered at a temperature ranging from 700° to 850° C. over a period of two hours. Subsequently, chemical reactions occurred between the powders. The so-reacted sintered powders were crushed to particles having a diameter of a few microns and were blended again with each other so as to obtain a powdered mixture. A predetermined amount of binder of polyvinyl alcohol (PVA) was added into the powdered mixture, which was then shaped under a shaping pressure of approximately 3 tons/cm² into discs having a diameter of 16.5 mm and a thickness of 0.6 mm. The shaped discs were air-tightly sealed in a magnesia ceramic vessel so as to prevent the lead component from being evaporated from the discs during sintering. The final sintering was carried out over a period of two hours, and ceramic bodies were produced. Thereafter, a silver electrode was baked onto each side of the ceramic bodies. The ceramic bodies with the pair of electrodes were used as samples for measuring electrical properties, i.e., the dielectric constant (ε_(s) at 1 KHz at 20° C.) the dielectric loss (tan δ at 1 KHz at 20° C.) and the insulation resistance (IR). The temperature dependence of the dielectric constant (ε_(s) at 1 KHz) was measured with regard to several samples. The measurement results are shown in Table 1. The asterisked samples all of the tables below designate the control samples unless otherwise mentioned.

                                      TABLE 1                                      __________________________________________________________________________                                     Electric Properties                                Basic Ingredients                                                                           Proportion of Basic Oxides                                                                             Temperature    Sintering              Sample                                                                             (mol %)      (wt %)                  Dependence (%) Temperature            No. Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         PbO MgO Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         ε.sub.s                                                                    tan δ(%)                                                                      -25° C.                                                                      +85° C.                                                                      IR (Ω)                                                                        (°C.)           __________________________________________________________________________      1* 100     0    68.63                                                                              4.13                                                                               27.24                                                                              0   9800                                                                              0.1  +49  -59.2                                                                               3 × 10.sup.10                                                                 1150                   2   99      1    68.67                                                                              4.09                                                                               26.99                                                                              0.25                                                                              14200                                                                              0.2  +26.0                                                                               -68.5                                                                               4 × 10.sup.10                                                                 1130                   3   97      3    68.76                                                                              4.02                                                                               26.48                                                                              0.74                                                                              20000                                                                              0.4  -35.0                                                                               -65.0                                                                               6 × 10.sup.10                                                                 1100                   4   95      5    68.86                                                                              3.94                                                                               25.97                                                                              1.23                                                                              21400                                                                              1.3  -39.3                                                                               -62.6                                                                               3 × 10.sup.10                                                                 1100                   5   93      7    68.95                                                                              3.86                                                                               25.46                                                                              1.73                                                                              20950                                                                              1.8  -61.8                                                                               -52.3                                                                               1 ×                                                                           1100up.10              6   91      9    69.05                                                                              3.78                                                                               24.94                                                                              2.23                                                                              18900                                                                              3.5  -65.1                                                                               -36.6                                                                               2 × 10.sup.10                                                                 1100                   7   88      12   69.19                                                                              3.67                                                                               24.17                                                                              2.97                                                                              16200                                                                              4.8  -66.6                                                                               +32.0                                                                               2 × 10.sup.10                                                                 1100                    8* 85      15   69.34                                                                              3.55                                                                               23.39                                                                              3.72                                                                               9000                                                                              8.8  -74.4                                                                               +89.0                                                                               1 × 10.sup.10                                                                 1100                   __________________________________________________________________________

EXAMPLE 2

The procedure of Example 1 was repeated, except that tungsten oxides (WO₃) was used as one of the starting ingredients. The measurement results are shown in Table 2. The asterisked samples in Table 2 fall within the composition range of the basic ceramic composition.

                                      TABLE 2                                      __________________________________________________________________________         Basic Ingredients                                                                           Additive                                                                                Proportion of                                        Sample                                                                             (mol %)      Parts by weight                                                                        Basic Oxides (wt %)                                   No. Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         Pb(Mn.sub.2/3 W.sub.1/3)O.sub.3                                                        PbO  MgO Nb.sub.2 O.sub.5                                                                    TiO.sub.2                               __________________________________________________________________________      9* 97      3    0       68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    10  97      3    0.05    68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    11  97      3    0.1     68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    12  97      3    0.5     68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    13  97      3    1.0     68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    14  97      3    3.0     68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    15  97      3    5.0     68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    16* 97      3    8.0     68.76                                                                               4.02                                                                               26.48                                                                               0.74                                    17* 95      5    0       68.86                                                                               3.94                                                                               25.97                                                                               1.23                                    18  95      5    0.3     68.86                                                                               3.94                                                                               25.97                                                                               1.23                                    19  95      5    0.6     68.86                                                                               3.94                                                                               25.97                                                                               1.23                                    20  95      5    2.0     68.86                                                                               3.94                                                                               25.97                                                                               1.23                                    21* 95      5    9.0     68.86                                                                               3.94                                                                               25.97                                                                               1.23                                    22* 93      7    0       68.95                                                                               3.86                                                                               25.46                                                                               1.73                                    23  93      7    0.2     68.95                                                                               3.86                                                                               25.46                                                                               1.73                                    24  93      7    0.5     68.95                                                                               3.86                                                                               25.46                                                                               1.73                                    25  93      7    1.5     68.95                                                                               3.86                                                                               25.46                                                                               1.73                                    26* 93      7    10.0    68.95                                                                               3.86                                                                               25.46                                                                               1.73                                    __________________________________________________________________________                 Electric Properties                                                    Additive         Temperature    Sintering                                  Sample                                                                             Parts by Weight  Dependence     Temperature                                No. Pb(Mn.sub.2/3 W.sub.1/2)O.sub.3                                                        ε.sub.s                                                                    tan δ(%)                                                                      -25° C.                                                                      +85° C.                                                                      IR (Ω)                                                                        (°C.)                               __________________________________________________________________________      9* 0       20000                                                                              0.4  -35.0                                                                               -65.0                                                                               6 × 10.sup.10                                                                 1100                                       10  0.05    20900                                                                              0.5  -34.8                                                                               -64.5                                                                               4 × 10.sup.11                                                                 1060                                       11  0.1     20630                                                                              0.2  -34.9                                                                               -63.9                                                                               1 × 10.sup.12                                                                 1060                                       12  0.5     20000                                                                              0.1  -33.1                                                                               -64.0                                                                               9 × 10.sup.11                                                                 1040                                       13  1.0     18970                                                                              0.1  -33.0                                                                               -62.8                                                                               8 × 10.sup.11                                                                 1020                                       14  3.0     16200                                                                              0.1  -31.8                                                                               -59.0                                                                               6 × 10.sup.11                                                                 1000                                       15  5.0     14000                                                                              0.1  -30.0                                                                               -58.5                                                                               4 × 10.sup.11                                                                  990                                       16* 8.0      6050                                                                              0.2  -20.5                                                                               -41.8                                                                               4 × 10.sup.10                                                                  990                                       17* 0       21400                                                                              1.3  -39.3                                                                               -62.6                                                                               3 × 10.sup.10                                                                 1100                                       18  0.3     21900                                                                              1.2  -38.1                                                                               -61.3                                                                               2 × 10.sup.11                                                                 1050                                       19  0.6     20800                                                                              0.9  -37.5                                                                               -62.5                                                                               3 × 10.sup.12                                                                 1050                                       20  2.0     17200                                                                              0.5  -34.8                                                                               -60.8                                                                               9 ×  10.sup.11                                                                1020                                       21* 9.0      4970                                                                              0.4  -18.1                                                                               -21.7                                                                               3 × 10.sup.10                                                                  990                                       22* 0       20950                                                                              1.8  -61.8                                                                               -52.3                                                                               1 × 10.sup.10                                                                 1100                                       23  0.2     20800                                                                              1.0  -60.9                                                                               -51.8                                                                               7 × 10.sup.10                                                                 1020                                       24  0.5     19950                                                                              0.9  -58.7                                                                               -51.1                                                                               3 × 10.sup.11                                                                  980                                       25  1.5     15400                                                                              0.5  -48.5                                                                               -41.7                                                                               9 × 10.sup.11                                                                  980                                       26* 10.0     5010                                                                              0.6  -28.0                                                                               -39.0                                                                               2 × 10.sup.10                                                                  960                                       __________________________________________________________________________

EXAMPLE 3

The procedure of Example 1 was repeated, except that manganese oxide (MnO) was used as one of the starting ingredients. The measurement results are shown in Table 3. The asterisked samples in Table 3 fall within the composition range of the basic ceramic composition.

                                      TABLE 3                                      __________________________________________________________________________                                                                Sin-                                                     Electric Properties   tering                                                           Temperature   Tem-                Sam-                                                                              Basic Ingredients                                                                           Additive                                                                               Proportion           Dependence    per-                ple                                                                               (mol %)      Parts by weight                                                                        of Basic Oxides (wt %)                                                                          tan -25°                                                                        +85°                                                                              ature               No.                                                                               Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         ε.sub.s                                                                    δ(%)                                                                         C.  C.  IR                                                                                   (°C.)        __________________________________________________________________________     27*                                                                               97      3    0       68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20000                                                                              0.4 -35.0                                                                              -65.0                                                                              6 × 10.sup.10                                                                  1100                28 97      3    0.05    68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              21200                                                                              0.3 -34.1                                                                              -64.7                                                                              8 × 10.sup.10                                                                  1060                29 97      3    0.1     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20900                                                                              0.3 -34.8                                                                              -62.7                                                                              2 × 10.sup.11                                                                  1040                30 97      3    0.5     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20300                                                                              0.2 -32.9                                                                              -63.9                                                                              5 × 10.sup.11                                                                  1040                31 97      3    1.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              19200                                                                              0.1 -32.9                                                                              -62.7                                                                              8 × 10.sup.11                                                                  1020                32 97      3    3.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              16300                                                                              0.1 -31.7                                                                              -58.8                                                                              7 × 10.sup.11                                                                  1000                33 97      3    5.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              13700                                                                              0.1 -30.1                                                                              -57.7                                                                              7 × 10.sup.10                                                                   990                34*                                                                               97      3    8.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                               6100                                                                              0.1 -19.8                                                                              -42.1                                                                              5 × 10.sup.10                                                                   980                35*                                                                               95      5    0       68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              21400                                                                              1.3 -39.3                                                                              -62.6                                                                              3 × 10.sup.10                                                                  1100                36 95      5    0.3     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              22900                                                                              0.8 -35.8                                                                              -60.8                                                                              5 × 10.sup.11                                                                  1060                37 95      5    0.6     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              20800                                                                              0.6 -37.7                                                                              -62.5                                                                              1 × 10.sup.12                                                                  1040                38 95      5    2.0     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              15700                                                                              0.4 -33.9                                                                              -61.1                                                                              8 × 10.sup.11                                                                  1020                39*                                                                               95      5    9.0     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                               5700                                                                              0.3 -17.7                                                                              -21.8                                                                              5 × 10.sup.10                                                                  1000                40*                                                                               93      7    0       68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20950                                                                              1.8 -61.8                                                                              -52.3                                                                              1 × 10.sup.10                                                                  1100                41 93      7    0.2     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              21000                                                                              1.4 -60.0                                                                              -52.1                                                                              7 × 10.sup.10                                                                  1020                42 93      7    0.5     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20000                                                                              1.0 -57.8                                                                              -50.8                                                                              6 × 10.sup.11                                                                   980                43 93      7    1.5     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              16600                                                                              0.8 -48.1                                                                              -40.2                                                                              7 × 10.sup.11                                                                   980                44*                                                                               93      7    10.0    68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                               4700                                                                              0.7 -28.8                                                                              -38.9                                                                              2 × 10.sup.10                                                                   980                __________________________________________________________________________

EXAMPLE 4

The procedure of Example 1 was repeated, except that manganese oxide (MnO) and tantalum oxide (Ta₂ O₅) were used as parts of the starting ingredients. The measurement results are shown in Table 4. The asterisked samples fall within the composition range of the basic ceramic composition.

                                      TABLE 4                                      __________________________________________________________________________                                                                Sin-                                                                           tering                                                  Electric Properties    Tem-                Sam-                                                                              Basic Ingredients                                                                          Additive                                                                               Proportion           Temperature    per-                ple                                                                               (mol %)     Parts by weight                                                                        of Basic Oxides (wt %)                                                                          tan δ                                                                        Dependence     ature               No.                                                                               PB(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                        Pb(Mn.sub.1/3 Ta.sub.2/3)O.sub.3                                                       PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         ε.sub.s                                                                    (%) -25° C.                                                                      +85° C.                                                                      IR                                                                                  (°C.)        __________________________________________________________________________     45*                                                                               97      3   0       68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20000                                                                              0.4 -35.0                                                                               -65.0                                                                               6                                                                              × 10.sup.10                                                                   1100                46 97      3   0.05    68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              21350                                                                              0.3 -34.1                                                                               -63.7                                                                               9                                                                                   1080es. 10.sup.     0                                                                              47 97      3   0.1     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20900                                                                              0.3 -34.2                                                                               -62.8                                                                               5                                                                                   1060es. 10.sup.     1                                                                              48 97      3   0.5     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20100                                                                              0.2 -32.7                                                                               -63.1                                                                               2                                                                                   1060es. 10.sup.     2                                                                              49 97      3   1.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              18970                                                                              0.2 -32.7                                                                               -61.9                                                                               6                                                                                   1040es. 10.sup.     1                                                                              50 97      3   3.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              16300                                                                              0.1 -30.9                                                                               -57.7                                                                               4                                                                                   1020es. 10.sup.     1                                                                              51 97      3   3.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              14100                                                                              0.1 -30.3                                                                               -51.5                                                                               2                                                                                   1000es. 10.sup.     1                                                                              52*                                                                               97      3   8.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                               5990                                                                              0.2 -21.1                                                                               -40.8                                                                               3                                                                                   1000es. 10.sup.     0                                                                              53*                                                                               95      5   0       68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              21400                                                                              1.3 -39.3                                                                               -62.6                                                                               3                                                                                   1100es. 10.sup.     0                                                                              54 95      5   0.3     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              22800                                                                              1.1 -37.7                                                                               -59.8                                                                               5                                                                                   1080es. 10.sup.     1                                                                              55 95      5   0.6     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              20910                                                                              0.8 -37.6                                                                               -57.7                                                                               2                                                                                   1060es. 10.sup.     2                                                                              56 95      5   2.0     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              16000                                                                              0.6 -33.9                                                                               -54.8                                                                               8                                                                                   1040es. 10.sup.     1                                                                              57*                                                                               95      5   9.0     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                               3100                                                                              0.4 -19.9                                                                               -51.9                                                                               7                                                                                   1000es. 10.sup.     0                                                                              58*                                                                               93      7   0       68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20950                                                                              1.8 -61.8                                                                               -52.3                                                                               1                                                                                   1100es. 10.sup.     0                                                                              59 93      7   0.2     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20200                                                                              1.5 -59.8                                                                               -50.9                                                                               9                                                                                   1080es. 10.sup.     0                                                                              60 93      7   0.5     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              19900                                                                              1.0 -57.8                                                                               -50.1                                                                               7                                                                                   1060es. 10.sup.     1                                                                              61 93      7   1.5     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              15100                                                                              0.7 -44.4                                                                               -48.8                                                                               8                                                                                   1040es. 10.sup.     1                                                                              62*                                                                               93      7   10.0    68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                               5200                                                                              0.8 -24.5                                                                               -39.7                                                                               6                                                                                   1040es. 10.sup.     __________________________________________________________________________

EXAMPLE 5

The procedure of Example 1 was repeated, except that tungsten oxide (WO₃) and manganese oxide (MnO) were used as parts of the starting ingredients. The measurement results are shown in Table 5. The asterisked samples fall within the composition range of the basic ceramic composition.

                                      TABLE 5                                      __________________________________________________________________________                                                                Sin-                                                     Electric Properties   tering                                                           Temperature   Tem-                Sam-                                                                              Basic Ingredients                                                                           Additive                                                                               Proportion           Dependence    per-                ple                                                                               (mol %)      Parts by weight                                                                        of Basic Oxides (wt %)                                                                          tan -25°                                                                        +85°                                                                              ature               No.                                                                               PB(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3                                                        PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         ε.sub.s                                                                    δ(%)                                                                         C.  C.  IR                                                                                   (°C.)        __________________________________________________________________________     63*                                                                               97      3    0       68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20000                                                                              0.4 -35.0                                                                              -65.0                                                                              6 × 10.sup.10                                                                  1100                64 97      3    0.05    68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20900                                                                              0.3 -34.8                                                                              -61.9                                                                              7 × 10.sup.11                                                                  1060                65 97      3    0.1     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20750                                                                              0.2 -33.8                                                                              -63.5                                                                              2 × 10.sup.12                                                                  1060                66 97      3    0.5     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20300                                                                              0.1 -32.9                                                                              -64.0                                                                              8 × 10.sup.11                                                                  1040                67 97      3    1.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              19150                                                                              0.1 -32.9                                                                              -61.7                                                                              4 × 10.sup.11                                                                  1020                68 97      3    3.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              16270                                                                              0.1 -31.9                                                                              -58.8                                                                              2 × 10.sup.11                                                                  1000                69 97      3    5.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              13700                                                                              0.1 -29.0                                                                              -56.0                                                                              9 × 10.sup.10                                                                   990                70*                                                                               97      3    8.0     68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                               5970                                                                              0.2 -18.9                                                                              -38.8                                                                              2 × 10.sup.10                                                                   990                71*                                                                               95      5    0       68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              21400                                                                              1.3 -39.3                                                                              -62.6                                                                              3 × 10.sup.10                                                                  1100                72 95      5    0.3     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              22900                                                                              0.9 -36.6                                                                              -59.8                                                                              4 × 10.sup.11                                                                  1050                73 95      5    0.6     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              20150                                                                              0.7 -35.4                                                                              -59.7                                                                              2 × 10.sup.12                                                                  1050                74 95      5    2.0     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              16000                                                                              0.4 -27.8                                                                              -54.5                                                                              9 × 10.sup.11                                                                  1020                75*                                                                               95      5    9.0     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                               5500                                                                              0.2 -18.9                                                                              -23.7                                                                              6 × 10.sup.10                                                                   990                76*                                                                               93      7    0       68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20950                                                                              1.8 -61.8                                                                              -52.3                                                                              1 × 10.sup.10                                                                  1100                77 93      7    0.2     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20900                                                                              1.5 -58.5                                                                              -50.8                                                                              6 × 10.sup.10                                                                  1020                78 93      7    0.5     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              20000                                                                              1.1 -54.7                                                                              -50.5                                                                              8 × 10.sup.11                                                                   980                79 93      7    1.5     68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              16200                                                                              0.6 -46.6                                                                              -40.8                                                                              6 × 10.sup.11                                                                   980                80*                                                                               93      7    10.0    68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                               4950                                                                              0.7 -21.5                                                                              -40.0                                                                              3 × 10.sup.10                                                                   960                __________________________________________________________________________

EXAMPLE 6

The procedure of Example 1 was repeated, except that manganese oxide (MnO) was used as one of the starting ingredients. The measurement results are shown in Table 6. The asterisked samples fall within the composition range of the basic ceramic composition.

                                      TABLE 6                                      __________________________________________________________________________                      Add-             Add-                                                                               Electric Properties  Sin-                                 itive            itive       Temperature  tering                               Parts            Parts       Depend-      Tem-                Sam-                                                                               Basic Ingredients                                                                           by  Proportion of                                                                               by          ence (%)     per-                ple (mol %)      weight                                                                             Basic Oxides (wt %)                                                                         weight  tan -25°                                                                        +85°                                                                             ature               No. Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         MnO PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         MnO ε.sub.s                                                                    δ(%)                                                                         C.  C.  IR                                                                                  (°C.)        __________________________________________________________________________     81* 97      3    0   68.76                                                                              4.02                                                                             26.48                                                                              0.74                                                                              0   20000                                                                              0.4 -35.0                                                                              -65.0                                                                              6                                                                              × 10.sup.10                                                                   1100                82  97      3    0.005                                                                              68.76                                                                             4.02                                                                              26.40                                                                              0.74                                                                              0.005                                                                              20850                                                                              0.3 -36.1                                                                              -64.8                                                                              8                                                                                   1100es. 10.sup.     0                                                                              83  97      3    0.01                                                                               68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              0.01                                                                               20150                                                                              0.3 -34.8                                                                              -65.1                                                                              3                                                                                   1080es. 10.sup.     1                                                                              84  97      3    0.2 68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              0.2 17200                                                                              0.2 -28.8                                                                              -58.9                                                                              8                                                                                   1060es. 10.sup.     1                                                                              85  97      3    0.5 68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              0.5 12200                                                                              0.1 -21.8                                                                              -33.0                                                                              5                                                                                   1040es. 10.sup.     1                                                                              86  97      3    1.0 68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              1.0  9870                                                                              0.1 -14.5                                                                              -27.1                                                                              9                                                                                   1040es. 10.sup.     1                                                                              87  97      3    1.3 68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              1.3  7850                                                                              0.1 -16.6                                                                              -24.2                                                                              7                                                                                   1020es. 10.sup.     1                                                                              88* 97      3    2.0 68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              2.0  4220                                                                              0.1 -18.8                                                                              -20.0                                                                              6                                                                                   1020es. 10.sup.     0                                                                              89* 95      5    0   68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0   21400                                                                              1.3 -39.3                                                                              -62.6                                                                              3                                                                                   1100es. 10.sup.     0                                                                              90  95      5    0.02                                                                               68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.02                                                                               20780                                                                              1.1 -41.1                                                                              -58.8                                                                              8                                                                                   1100es. 10.sup.     1                                                                              91  95      5    0.3 68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.3 16650                                                                              0.8 -36.6                                                                              -57.5                                                                              9                                                                                   1080es. 10.sup.     1                                                                              92  95      5    1.5 68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              1.5  7020                                                                              0.5 -24.2                                                                              -30.8                                                                              7                                                                                   1040es. 10.sup.     1                                                                              93* 95      5    3.0 68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              3.0  3950                                                                              0.4 -19.5                                                                              -22.0                                                                              5                                                                                   1020es. 10.sup.     0                                                                              94  93      7    0   68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              0   20950                                                                              1.8 -61.8                                                                              -52.3                                                                              1                                                                                   1100es. 10.sup.     0                                                                              95  93      7    0.001                                                                              68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              0.001                                                                              21000                                                                              1.5 -60.5                                                                              -53.8                                                                              6                                                                                   1100es. 10.sup.     1                                                                              96  93      7    0.03                                                                               68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              0.03                                                                               20990                                                                              1.1 -58.8                                                                              -52.1                                                                              1                                                                                   1080es. 10.sup.     2                                                                              97  93      7    0.3 68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              0.3 15200                                                                              0.8 -48.9                                                                              -42.0                                                                              8                                                                                   1060es. 10.sup.     1                                                                              98  93      7    1.0 68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              1.3 10880                                                                              0.7 -32.9                                                                              -41.5                                                                              5                                                                                   1040es. 10.sup.     1                                                                              99* 93      7    3.0 68.95                                                                             3.86                                                                              25.46                                                                              1.73                                                                              3.0  4020                                                                              0.8 -18.5                                                                              -20.5                                                                              3                                                                                   1020es. 10.sup.     __________________________________________________________________________

EXAMPLE 7

The procedure of Example 1 was repeated so as to produce the ceramic compositions as shown in Table 7. The measurement results are shown in Table 7. The asterisked samples Nos. 102 and 110 fall within the composition range of the basic ceramic composition.

                                      TABLE 7                                      __________________________________________________________________________                                           Electric Properties  Sin-                                                              Temperature  tering                               Excess                       Depend-      Tem-                Sam-                                                                               Basic Ingredients                                                                           MgO Proportion of                                                                               Excess      ence (%)     per-                ple (mol %)      Wt. Basic Oxides (wt %)                                                                         MgO     tan -25°                                                                        +85°                                                                             ature               No. PB(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         Part                                                                               PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         (wt %)                                                                             ε.sub.s                                                                    δ(%)                                                                         C.  C.  IR                                                                                  (°C.)        __________________________________________________________________________     100*                                                                               99      1    0   63.67                                                                             4.09                                                                              26.99                                                                              0.25                                                                              0   14200                                                                              0.2 +26.0                                                                              -68.5                                                                              4                                                                              × 10.sup.10                                                                   1150                101 99      1    10  68.67                                                                             4.09                                                                              26.99                                                                              0.25                                                                              0.409                                                                              19800                                                                              0.3 +28.5                                                                              -66.0                                                                              8                                                                                   1100es. 10.sup.     1                                                                              102*                                                                               95      5    0   68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0   21400                                                                              1.3 -39.3                                                                              -62.6                                                                              3                                                                                   1100es. 10.sup.     0                                                                              103 95      5    3   68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.118                                                                              22500                                                                              1.2 -42.1                                                                              -58.7                                                                              8                                                                                   1050es. 10.sup.     0                                                                              104 95      5    6   68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.236                                                                              24700                                                                              1.4 -47.4                                                                              -63.1                                                                              2                                                                                   1050es. 10.sup.     2                                                                              105 95      5    9   68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.353                                                                              30100                                                                              1.3 -40.8                                                                              -60.5                                                                              1                                                                                   1050es. 10.sup.     2                                                                              106 95      5    15  68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.591                                                                              26200                                                                              1.4 -41.3                                                                              -59.0                                                                              3                                                                                   1050es. 10.sup.     2                                                                              107 95      5    20  68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.788                                                                              23800                                                                              1.4 -39.5                                                                              -62.0                                                                              7                                                                                   1050es. 10.sup.     1                                                                              108 95      5    25  68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              0.985                                                                              21900                                                                              1.6 -40.2                                                                              -61.8                                                                              3                                                                                   1050es. 10.sup.     1                                                                              109*                                                                               95      5    30  68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              1.182                                                                              17700                                                                              1.5 -40.8                                                                              -58.8                                                                              6                                                                                   1080es. 10.sup.     0                                                                              110*                                                                               91      9    0   69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              0   18900                                                                              3.5 -65.1                                                                              -36.6                                                                              2                                                                                   1100es. 10.sup.     0                                                                              111 91      9    10  69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              0.378                                                                              26800                                                                              2.8 -62.0                                                                              -37.7                                                                              9                                                                                   1050es. 10.sup.     1                                                                              112*                                                                               91      9    30  69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              1.134                                                                              15100                                                                              2.6 -61.1                                                                              -40.5                                                                              3                                                                                   1100es. 10.sup.     0                                                                              113*                                                                               85      15   0   69.34                                                                             3.55                                                                              23.39                                                                              3.72                                                                              0   9000                                                                               8.8 -74.4                                                                              +85 1                                                                                   1100es. 10.sup.     0                                                                              114*                                                                               85      15   10  69.34                                                                             3.55                                                                              23.39                                                                              3.72                                                                              0.355                                                                              9880                                                                               9.3 -75.2                                                                              +86.6                                                                              2                                                                                   1050es. 10.sup.     __________________________________________________________________________

EXAMPLE 8

The procedure of Example 1 was repeated, except that barium carbonates (BaCO₃), strontium carbonate (SrCO₃) and calcium carbonate (CaCO₃) were used as parts of the starting ingredients. The measurement results are shown in Table 8. The asterisked samples Nos. 115, 119 and 126 fall within the composition range of the basic ceramic composition.

                                      TABLE 8                                      __________________________________________________________________________                                            Electric Properties Sin-                                     Re-                      Temperature  tering                               Re- placing                  Depend-      Tem-                Sam-                                                                               Basic Ingredients                                                                           placing                                                                            A-  Proportion           ence (%)     per-                ple (mol %)      Ele-                                                                               mount                                                                              of Basic Oxides (wt %)                                                                          tan -25°                                                                        +85°                                                                             ature               No. Pb(Mg.sub.1/3 Mb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         ment                                                                               (wt %)                                                                             PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         ε.sub.s                                                                    δ (%)                                                                        C.  C.  IR                                                                                  (°C.)        __________________________________________________________________________     115*                                                                               97      3    none                                                                               0   68.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20000                                                                              0.4 -35.0                                                                              -65.0                                                                              6                                                                              × 10.sup.10                                                                   1100                116 97      3    Ba  3   65.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              21100                                                                              0.3 -34.8                                                                              -64.2                                                                              7                                                                                   1080es. 10.sup.     0                                                                              117 97      3    Ba  5   63.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              21800                                                                              0.3 -36.0                                                                              -66.1                                                                              2 ×                                                                      10.sup.11                                                                           1060                118 97      3    Ba  10  58.76                                                                             4.02                                                                              26.48                                                                              0.74                                                                              20750                                                                              0.2 -32.7                                                                              -63.5                                                                              8                                                                                   1020es. 10.sup.     0                                                                              119*                                                                               95      5    none                                                                               0   68.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              21400                                                                              1.3 -39.3                                                                              -62.6                                                                              3                                                                                   1100es. 10.sup.     0                                                                              120 95      5    Ba  1   67.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              21600                                                                              1.1 -40.5                                                                              -61.8                                                                              3                                                                                   1100es. 10.sup.     0                                                                              121 95      5    Ba  5   63.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              23300                                                                              0.8 -41.3                                                                              -59.8                                                                              6                                                                                   1100es. 10.sup.     0                                                                              122 95      5    Sr  1   67.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              22500                                                                              1.2 -38.8                                                                              -64.4                                                                              8                                                                                   1100es. 10.sup.     0                                                                              123 95      5    Sr  10  58.76                                                                             3.94                                                                              25.97                                                                              1.23                                                                              24700                                                                              0.7 -42.4                                                                              -60 2                                                                                   1100es. 10.sup.     1                                                                              124 95      5    Sr  15  53.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              19400                                                                              0.7 -41.8                                                                              -59.8                                                                              5                                                                                   1100es. 10.sup.     1                                                                                               Ba  2                                                         125 95      5    Sr  2   63.86                                                                             3.94                                                                              25.97                                                                              1.23                                                                              22500                                                                              1.0 -42.0                                                                              -60.8                                                                              4                                                                                   1060es. 10.sup.     1                                                                                               Ca  1                                                         126 91      9    none                                                                               0   69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              18900                                                                              3.5 -65.1                                                                              -36.6                                                                              2 ×                                                                      10.sup.10                                                                           1100                127 91      9    Ca  2   67.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              19400                                                                              2.8 -62.8                                                                              -40.3                                                                              4                                                                                   1100es. 10.sup.     0                                                                              128 91      9    Ba  10  59.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              20800                                                                              2.9 -66.6                                                                              -35.8                                                                              6                                                                                   1080es. 10.sup.     0                                                                              129*                                                                               91      9    Ba  15  54.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              16300                                                                              3.0 -67.5                                                                              -41.7                                                                              1                                                                                   1080es. 10.sup.     0                                                                              130 91      9    Sr  4   65.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              2.200                                                                              2.7 -64.4                                                                              -32.4                                                                              7                                                                                   1100es. 10.sup.     __________________________________________________________________________

EXAMPLE 9

The procedure of Example 1 was repeated so as to produce the ceramic compositions as shown in Table 9. The measurement results are shown in Table 9. The asterisked samples Nos. 131 and 145 fall within the composition range of the basic ceramic composition.

                                      TABLE 9                                      __________________________________________________________________________                                                                Sin-                                                                           tering                                Excess Amount      Electric Properties   Tem-                    Basic Ingredients                                                                            Additive                                                                              of                  Temperature   per-                Sample                                                                             (mol %)       of     Additive                                                                              Ratio of tan Dependence(%) ature               No. Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                        PbTiO.sub.3                                                                         B site (wt %) A/B sites                                                                           ε.sub.s                                                                    δ(%)                                                                         -25°C.                                                                      +85°C.                                                                       IR                                                                                  (°C.)        __________________________________________________________________________     131*                                                                               94       6      none 0      1.0000                                                                              20800                                                                              1.0 -36.4                                                                              -63.1                                                                               6                                                                              × 10.sup.10                                                                   1100                132 94       6      MgO  0.23   0.9819                                                                              24500                                                                              1.4 -46.6                                                                              -64.8                                                                               8                                                                                   1050es. 10.sup.     0                                                                              133 94       6      "    0.35   0.9727                                                                              29800                                                                              1.2 -42.1                                                                              -65.8                                                                               2                                                                                   1050es. 10.sup.     1                                                                              134 94       6      "    0.59   0.9548                                                                              27800                                                                              1.3 -40 -63.7                                                                               4                                                                                   1050es. 10.sup.     1                                                                              135 94       6      "    1.01   0.9247                                                                              22200                                                                              1.4 -38.9                                                                              -66.1                                                                               2                                                                                   1050es. 10.sup.     1                                                                              136*                                                                               94       6      "    1.29   0.9064                                                                              17100                                                                              1.6 -40.1                                                                              -66.2                                                                               4                                                                                   1100es. 10.sup.     0                                                                              137 94       6      Nb.sub.2 O.sub.5                                                                    0.77   0.9817                                                                              21900                                                                              1.2 -38.7                                                                              -63.5                                                                               7                                                                                   1100es. 10.sup.     0                                                                              138 94       6      "    1.29   0.9700                                                                              26800                                                                              1.2 -42.3                                                                              -65.0                                                                               1                                                                                   1100es. 10.sup.     1                                                                              139 94       6      "    2.57   0.9411                                                                              24400                                                                              1.3 -41.0                                                                              -62.7                                                                               1                                                                                   1100es. 10.sup.     1                                                                              140*                                                                               94       6      "    3.86   0.9120                                                                              16200                                                                              1.5 -40.8                                                                              -59.7                                                                               3                                                                                   1150es. 10.sup.     0                                                                              141 94       6      TiO.sub.2                                                                           0.13   0.9949                                                                              23900                                                                              1.6 -42.7                                                                              -61.2                                                                               8                                                                                   1050es. 10.sup.     0                                                                              142 94       6      "    0.44   0.9824                                                                              26200                                                                              1.7 -43.3                                                                              -65.5                                                                               9                                                                                   1050es. 10.sup.     0                                                                              143 94       6      "    1.18   0.9548                                                                              24400                                                                              1.5 -46.5                                                                              -64.5                                                                               1                                                                                   1050es. 10.sup.     1                                                                              144 94       6      "    1.63   0.9382                                                                              22100                                                                              1.4 -39.0                                                                              -62.7                                                                               2                                                                                   1050es. 10.sup.     1                                                                              145 96       4      none 0      1.0000                                                                              20300                                                                              0.8 -32.1                                                                              -62.7                                                                               5                                                                                   1100es. 10.sup.     0                                                                              146 96       4      TiO.sub.2                                                                           0.75   0.9700                                                                              27700                                                                              1.3 -39.0                                                                              -66.1                                                                               2                                                                                   1050es. 10.sup.     1                                                                                                  TiO.sub.2                                                                           0.35                                                  147 96       4                  0.9705                                                                              29100                                                                              1.4 -42.1                                                                              -66.0                                                                               6                                                                                   1050es. 10.sup.     1                                                                                                  MgO  0.20                                                  __________________________________________________________________________

EXAMPLE 10

The procedure of Example 1 was repeated, except that tungsten oxide (WO₃) and bismuth oxide (Bi₂ O₃) were used as parts of the starting ingredients. The measurement results are shown in Table 10. The asterisked sample No. 151 falls within the composition range of the basic ceramic composition.

                                      TABLE 10                                     __________________________________________________________________________                                                                Sin-                                                                           tering                                                  Electric Properties    Tem-                Sam-                                                                              Basic Ingredients                                                                           Additive                                                                              Proportion           Temperature    per-                ple                                                                               %)           (wt %) of Basic Oxides (wt. %)                                                                         tanδ                                                                         Dependence     ature               No.                                                                               Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         Bi.sub.2 O.sub.3                                                                   WO.sub.3                                                                          Pbo                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                                                                         ε.sub.s                                                                    (%) -25° C.                                                                      +85° C.                                                                      IR                                                                                  (°C.)        __________________________________________________________________________      148*                                                                             100     0    0   0  68.63                                                                             4.13                                                                              27.24                                                                              0  9800                                                                               0.1 +49  -55.2                                                                               3                                                                              × 10.sup.10                                                                   1150                 149*                                                                             100     0    6   0  68.63                                                                             4.13                                                                              27.24                                                                              0  1200                                                                               0.2 +66  -42.0                                                                               8 × 10.sup.9                                                                  1100                 150*                                                                             100     0    0   6  68.63                                                                             4.13                                                                              27.24                                                                              0  1350                                                                               0.3 +69  -45  9 × 10.sup.9                                                                  1100                 151*                                                                             91      9    0   0  69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              18900                                                                              3.5   -65.1                                                                             -36.6                                                                               2                                                                                   1100es. 10.sup.     0                                                                              152                                                                               91      9      0.3                                                                              0  69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              16000                                                                              1.3 -45  -29.0                                                                               7                                                                                   1050es. 10.sup.     0                                                                              153                                                                               91      9    0     0.3                                                                             69.05                                                                             3.78                                                                              24.94                                                                              2.23                                                                              16500                                                                              1.4 -45  -30  8                                                                                   1050es. 10.sup.     0                                                                               154*                                                                             83      17   0   0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              4500                                                                               6.0 -48  +120 3                                                                                   1100es. 10.sup.     0                                                                              155                                                                               83      17     0.3                                                                              0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              5500                                                                               2.8 -39  +150 4                                                                                   1050es. 10.sup.     0                                                                              156                                                                               83      17   2   0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              10000                                                                              2.5 -35  +100 6                                                                                   1050es. 10.sup.     0                                                                              157                                                                               83      17   4   0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              13000                                                                              2.0 -40  -24  5                                                                                   1000es. 10.sup.     0                                                                              158                                                                               83      17   6   0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              6000                                                                               1.5 -30  -13  4                                                                                   1000es. 10.sup.     0                                                                              159                                                                               83      17   8   0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              4000                                                                               1.6 + 2  -17  3                                                                                    950es. 10.sup.     0                                                                               160*                                                                             83      17   10  0  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              2500                                                                               3.2 +14  -25  1                                                                                    950es. 10.sup.     0                                                                              161                                                                               83      17   0     0.3                                                                             69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              6000                                                                               2.9 -40  +140 3                                                                                   1050es. 10.sup.     0                                                                              162                                                                               83      17   0   2  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              11000                                                                              2.4 -36  +110 5                                                                                   1050es. 10.sup.     0                                                                              163                                                                               83      17   0   5  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              9700                                                                               1.8 -40  -26  7                                                                                   1000es. 10.sup.     0                                                                              164                                                                               83      17   0   8  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              4600                                                                               1.6 - 2  -15  4                                                                                    950es. 10.sup.     0                                                                               165*                                                                             83      17   0   10 69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              2700                                                                               4.2 +17  -27  8 × 10.sup.9                                                                   950                166                                                                               83      17     1.5                                                                                1.5                                                                             69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              11000                                                                              1.8 -35  -23  8                                                                                   1000es. 10.sup.     0                                                                              167                                                                               83      17   3   3  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              6500                                                                               1.6 -28  -15  5                                                                                    970es. 10.sup.     0                                                                              168                                                                               83      17   3   1  69.43                                                                             3.47                                                                              22.87                                                                              4.23                                                                              12500                                                                              1.8 -37  -25  4                                                                                    970es. 10.sup.     __________________________________________________________________________

EXAMPLE 11

The procedure of Example 10 was repeated except that an additive of Pb(Mn_(1/3) Nb_(2/3))O₃ was added to the sample No. 105. The measurement results are shown in Table 11.

                                      TABLE 11                                     __________________________________________________________________________         Basic Ingredients                                                                           Excess                                                                              Additive                                                                               Proportion of                                    Sample                                                                             (mol %)      MgO  (wt %)  Basic Oxides (wt %)                              No. Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbTiO.sub.3                                                                         wt. part                                                                            Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3                                                       PbO                                                                               MgO                                                                               Nb.sub.2 O.sub.5                                                                   TiO.sub.2                              __________________________________________________________________________     169 95      5    9    0.2     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                   170 95      5    9    0.5     68.86                                                                             3.94                                                                              25.97                                                                              1.23                                   __________________________________________________________________________                 Electric Properties                                                        Excess       Temperature    Sintering                                  Sample  MgO          Dependence (%) Temperature                                No.     (wt %)                                                                             ε.sub.s                                                                    tan δ (%)                                                                     -25° C.                                                                      +85° C.                                                                      IR (Ω)                                                                        (°C.)                               __________________________________________________________________________     169     0.353                                                                              30000                                                                              1.1  -40.5                                                                               -59.5                                                                               8 × 10.sup.11                                                                 1040                                       170     0.353                                                                              30100                                                                              0.9  -40.8                                                                               -60.1                                                                               9 × 10.sup.11                                                                 1040                                       __________________________________________________________________________ 

What we claim is:
 1. A high dielectric constant type ceramic composition, characterized in that said composition consists essentially of a basic ceramic composition of from 68.67 to 69.19% of PbO, from 3.67 to 4.09% of MgO, 24.17 to 26.99% of Nb₂ O₅ and from 0.25 to 2.97% of TiO₂, all percentages being by weight.
 2. A high dielectric constant type ceramic composition according to claim 1, characterized in that said composition comprises from 68.7 to 69.0% of PbO; from 3.85 to 4.05% of MgO; from 25.45 to 26.50% of Nb₂ O₅, and; from 0.70 to 1.75% of TiO₂.
 3. A high dielectric constant type ceramic composition according to claim 1, characterized in that said composition comprises said basic ceramic composition and Pb(Mn_(2/3) W_(1/3))O₃ in an amount of from 0.05 to 5.0 parts by weight, based on 100 weight parts of the basic ceramic composition.
 4. A high dielectric constant type ceramic composition according to claim 3, characterized in that the amount of said Pb(Mn_(2/3) W_(1/3))O₃ is from 0.1 to 0.6 parts by weight.
 5. A high dielectric constant type ceramic composition according to claim 1, characterized in that said composition comprises said basic ceramic composition and Pb(Mn_(1/3) Nb_(2/3))O₃ in an amount of from 0.05 to 5.0 parts by weight based on 100 weight parts of the basic ceramic composition.
 6. A high dielectric constant type ceramic composition according to claim 5, characterized in that the amount of said Pb(Mn_(1/3) Nb_(2/3))O₃ is from 0.1 to 1.0 part by weight.
 7. A high dielectric constant type ceramic composition according to claim 1, characterized in that said composition comprises said basic ceramic composition and Pb(Mn_(1/3) Ta_(2/3))O₃ in an amount of from 0.05 to 5.0 parts by weight based on 100 weight parts of the basic ceramic composition.
 8. A high dielectric constant type ceramic composition according to claim 7, characterized in that the amount of said Pb(Mn_(1/3) Ta_(2/3))O₃ is from 0.5 to 3.0 parts by weight.
 9. A high dielectric constant type ceramic composition according to claim 1, characterized in that said composition comprises said basic ceramic composition and Pb(Mn_(1/2) W_(1/2))O₃ in an amount of from 0.05 to 5.0 parts by weight, based on 100 weight parts of the basic ceramic composition.
 10. A high dielectric constant type ceramic composition according to claim 9, characterized in that the amount of said Pb(Mn_(1/2) W_(1/2))0₃ is from 0.1 to 1.5 parts by weight.
 11. A high dielectric constant type ceramic composition according to claim 1, characterized in that said composition comprises said basic ceramic composition and MnO in an amount of from 0.001 to 1.5 parts by weight, based on 100 weight parts of the basic ceramic composition.
 12. A high dielectric constant type ceramic composition according to claim 11, characterized in that the amount of said MnO is from 0.005 to 0.2 parts by weight.
 13. A high dielectric constant type ceramic composition according to claim 1, wherein said basic ceramic composition is mainly composed of a double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃ and a double oxide of PbTiO₃, characterized in that said composition comprises an Mg oxide additive in addition to said double oxides and the amount of the Mg oxide additive is not more than 25 parts by weight, based on 100 parts by weight of an Mg oxide contained in the double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃.
 14. A high dielectric constant type ceramic composition according to claim 13, characterized in that the amount of said Mg oxide additive is from 3 to 9 parts by weight.
 15. A high dielectric constant type ceramic composition according to claim 13, characterized in that said ceramic comprises Pb(Mn_(1/3) Nb_(2/3))O₃ in an amount of from 0.05 to 5.0 parts by weight based on 100 parts by weight of said double oxides.
 16. A high dielectric constant type ceramic composition according to claim 1, wherein said basic composition is mainly composed of a double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃ and a double oxide of PbTiO₃, characterized in that said composition comprises said basic ceramic composition and at least one additive element selected from the group consisting of barium, strontium and calcium in an amount of not more than 10 atomic parts, based on 100 atomic parts of lead contained in said double oxides.
 17. A high dielectric constant type ceramic composition according to claim 16, characterized in that the amount of said at least one additive element is from 3 to 10 atomic parts.
 18. A high dielectric constant type ceramic composition according to claim 1, wherein said basic ceramic composition is mainly composed of a double oxide of Pb(Mg_(1/3) Nb_(2/3))O₃ and a double oxide of PbTiO₃, and said double oxides are expressed by a form of A_(x) B_(y) O₃, characterized in that the molar ratio of A/B is from 0.9200 to less than 1.0000.
 19. A high dielectric constant type ceramic composition according to claim 18, characterized in that said molar ratio of A/B is from 0.950 to 0.982.
 20. A high dielectric constant type ceramic composition, characterized in that said composition consists essentially of from 60 to 98 molar% of Pb(Mg_(1/3) Nb_(2/3))O₃ and from 2 to 40 molar% of PbTiO₃, and further, from 0.2 to 8.0 parts by weight of at least one additive oxide selected from the group consisting of Bi₂ O₃ and WO₃, based on 100 parts by weight of total weight of Pb(Mg_(1/3) Nb_(2/3))O₃ and PbTiO₃.
 21. A high dielectric constant type ceramic composition according to claim 20, characterized in that the content of said at least one additive oxide is from 2 to 6 parts by weight. 